Construction of mercury switches



June 27, 1933.

E. M CABE' CONSTRUCTION OF MERCURY SWITCHES Filed July 31, 1951 INVENTORIRA E IVI CABE Maw/M ATTORNEY Patented June 27, 1933 UNITED STATES me a.moans, or cnroaeo, rumors oonsrnuorron or mnnounr sm'rca Applicationfiled July 31,

This invention relates to improvements in the construction of mercurytube switches and more particularly to that type in which a portion ofthe mercury is bodily raised by magnetic means to close and open thecircuit through the switch.

-Mercury tube switches including a sealed tube containing a quantity ofmercury and having spaced apart electrodes seated in the walls of thetube requiring the tilting of the switch to cause the mercury to flowinto and out of contact with the electrodes has a recognized place inthe switch art. There are times when it is neither practicable nordesirous to tilt a switch to open or close an electric circuittherethrough and it is an ob; ject of this invention to provide amercury tube switch with means for bodily moving a portion of themercury therein to open and :1) close the circuit therethrough while theswitch tube is stationary.

With these and other objects in view, reference is made to theaccompanying sheet of drawing whichillustrates a preferred form of thisinvention with the understanding that minor detail changes may be madewithout departing from the scope thereof.

In the drawing- Figure 1 is a view partly in vertical 'central sectionand partly in side elevation of this improved switch. before the fillingstem has been tipped ofi.

Figure 2 is a view in horizontal section, taken on the line 2-2, Figure1, looking in the direction of the arrows.

I Figure 3 is an enlarged detail view in perspective of the operatingparts removed from within the switch tube.

Figure 4' is aview similar to Figure 1 of a completed switch in openposition showing the positions of the interior and exterior operatingmeans.

Figure 5 is a view similar to Figure 4, illustrating the switch inclosed position..

I In the embodiment of this invention as illustrated, the container ortube 1 is preferably a glass tube closed at one end with electrodes 2and 3 welded upon leading in wired 2a and 3a, which wires with a fillingstem .4 between them are sealed in the other end and a body of mercury 5within the sealed tube. This switch is adapted to be firmly held withthe sealed end down, as shown. In order to I p bring the mercury intoand out of contact 1931. Serial No. waist.

with both electrodes the following constructlon is employed within thetube 1.

One electrode 2 is bent at right angles and is terminated in an eye 6about the lon itudinal axis of the tube 1 which acts as a guide for oneend of a longitudinally movable rod or shaft 7, preferably of the sameelectrical conductin The ot er end of the rod 7 is afixed to theunderside of a disc 8 of magnetic metal adapted to reciprocate withinthe tube 1, and provided with a small compression spring 9 on thesidenext to the closed end of the tube 1. Between the guiding eye 6 and thedisc 8 a cup 10 is centrally mounted upon the rod or shaft 7 with itstop opening in the direction of the disc 8. The other electrode 3 isconducted through a surrounding sleeve of glass 11, or other insulatingmaterial, to a point just above the uppermost travel of the cup 10 andis then bent over and back, so that when the cup 10 is at its lowermostpoint the end of the electrode 3 is spaced apart from the cup and at itsuppermost point the end of the electrode is received within the cup.

A. quantity of mercury 5 is contained with: in thetube 1 of sufiicientamount, so that when the cup 10 is at its lowermost point, the cup willbe submerged and the end of the electrode 3 will bespaced apartthereabove and out of contact. When the disc 8 and shaft 7 arereciprocated toward the closed .end of the tube, the cup 10 filled withmercury through the mercury in the cup 10, the shaft 7 and body ofmercury 5 in the tube to elecmaterial as the electrodes 2 and 3.

trode 2. As the cup 10 is submerged in the main body ofnthe .mercury ateach reciprocation, the contents of the cup is renewed after each breakof the circuit.

In the tilting mercury tube switch some external means is employed toimpart the I tilting movement to cause the mercury to flow into and outof contact with the two electrodes to close and open the circuit withinthe tube and likewise in this type where the tube does not tilt someexternal means must be employed to impart, reciprocatien to the rod orshaft 7 to carry the cup 10 full of mercury into and out of contact withthe electrode 3. It has been heretofore said that the disc 8 is ofmagnetic metal and, in this instance, a magnet 12 is arranged exteriorof the tube lwhich may be caused to approach and depart, by any known ordesired means, to and from the closed end of the tube 1 causing themagnetic disc 8 to be reciprocated The tube 1 to be operated must beheld with its sealed end lowermost. "W hen the magnet 12 approaches theclosed end of the tube 1 the disc 8 is attracted thereby causing the rodor shaft 7 to move through its lower guide 6 and bodily carry themercury contained in the cup into contact with the bent back end of theelectrode 3 to complete the circuit. The spring 9 on the top of the disc8 acts as a shock absorber to prevent the disc from breaking or crackingthe closed end of the tube 1. When the magnet 12 is moved away from thetube to remove the magnetic field from the disc 8, the weight of thedisc and associated parts causes the cup to descend and be submergedwithin the mercury 5 with n the bottom of the rod or shaft 7 restingupon the sealed end of the tube.

Switches of this type are made in a machine in which leading in wirescarrying the electrodes and a filling stem are held and positioned in aworkholder, the open end of a tube closed at the other end insertedthere on, the walls heated to plasticity and pressed together to embraceand seal the electrodes and filling-stem, as shown in Figure 1. Insealing theelectrodes in the glass bulb it is necessary that the wirehas the same coetiicient of expansion as the glass and it is commonpractice to weld a piece of such material to the electrodes as shown inthe drawing as 2a and awhich serve as lead in wires. As shown, thebottom of the rod or shaft 7 is expanded to form an enlarged base whichrests upon the open end of the filling stem 4 so that when the parts 2,6, 7 and 8 are assembled the electrode 2 may be placed in the workholder and position the parts during the sealing of the open end of thetube. The tube is reversed after sealing for theremoval of the containedair and insertion of the K mercury and inert gas through the fillingstein l, whereupon the parts 7 and 8 move away from the open end of thefilling stem. After the insertion of the mercury and gas the fillingstem 4 is tipped off as shown in Figures 4 and 5.

What I claim is:

1. A fluid switch including a sealed container, a body of electricconducting fluid therein, electrodes passing through the walls thereof,one entering and normally submerged in the conducting fluid and theother spaced apart therefrom, and means adapted to be reciprocatedwithin the container while in contact with the conducting fluid tobodily transport a portion of the conducting fluid upon thereciprocating means from the main body to contact the separatedelectrode to close the circuit, said means including a rodconductoroalways in contact with the said fluid and having a disc ofmagnetic material inducted carried thereon adapted to be reciprbcated byan external magnet.

2.. A fluid switch including a sealed container, a body of electricconducting fluid therein, electrodes passing through the walls thereof,one entering and normally sub merged in the conducting fluid and theother spaced apart therefrom, and means adapted to be reciprocatedwithin the container while in contact with the conducting fluid tobodily transport a portion 0:? the conducting upon the reciprocatingmeans fluid from the main .body to contact the separated electrode totainer, a body of electric conducting i'luid therein, electrodes passingthrough the walls thereof, one entering and normally submerged in theconducting fluid and the other spaced apart therefrom, and means adaptedto be reciprocated within the container while in contact with theconducting fluid to bodily transpert a portion of the conducting fluidfrom the main body to contact the separated electrode to close thecircuit, said means including a rod conductor always in contact with thesaid fluid and having a disc of magnetic material carried at one endthereon adapted to be reciprocated by an external magnet, and a cup uponthe rod normally submerged in the fluid at one end of its reciprocationadapted to bodily transport in the cup a portion of the fluid. tocontact the separated electrode at the other end of its reciprocation,

4. A fluid switch including a sealed tubu-x lar container, a body ofelectric conducting fluid therein, electrodes passing through the wallsthereof, one of which is normally submerged at all times in the saidfluid and is terminated in aneye about the longest axis of the containerand the other normally spaced apart and out of contact with the fluid, areciprocable conducting rod passing through the eye of the submergedelectrode terminating in a disc of magnetic material at the other endnormally spaced apart from the end of the container, and a cupsurrounding and attached to said rod between the electrode eye and thedisc normally submerged in the fluid, said disc adapted to be movedtoward the adjacent end of the container by an external .magnet to carrythe cup to submerge the separated electrode in its contained fluid toclose the circuit through the rod and main body of fluid to the otherelectrode and upon withdrawal of the field of the external magnet toallow the cup to depart from the spaced apart electrode to open thecircuit through the switch.

IRA ll. MoCABEK

